High thermoelectric performance of melt-spun Cu_xBi_0.5Sb_1.5Te₃ by synergetic effect of carrier tuning and phonon engineering

Bi-Te based materials have been used for near-room-temperature thermoelectric applications. However, their properties dramatically decrease at high temperatures (over 100 °C), limiting their use in power generation. In this study, we investigated the enhanced thermoelectric properties of Bi-Te based materials by Cu doping and employing the melt-spinning (MS) process that can be utilized especially at elevated temperatures. By changing the doping amount, we could modulate the temperature dependence of thermoelectric properties, where the maximum ZT temperature could be shifted from room temperature to 450 K. The highest ZT value, 1.34, was achieved at 400 K for 2% Cu-doped Bi_0.5Sb_1.5Te₃, which is due to the enhancement in power factor and reduction in lattice thermal conductivity. The average ZT value between room temperature and 530 K was 1.17 for 2% Cu-doped Bi_0.5Sb_1.5Te₃, which is 46% higher than that of pristine Bi_0.5Sb_1.5Te₃. Consequently, the synergetic effect of MS process and Cu incorporation can be a promising method to widen the application of Bi-Te based thermoelectric materials for mid-temperature power generation.